The results obtained on C14-glucose uptake and metabolism in vivo studies during this fiscal year revealed that the blood glucose is not a metabolic substrate for pig red cells, confirming the ample observations derived from in vitro experimentations. Similar in vivo assessment of glucose utilization and its metabolism of red cells of the newborn piglets is contemplated, since these cells lose their ability to utilize glucose according to the results gathered under in vitro conditions. If these results are confirmed, it would set a stage for conducting experimentations in search of in vivo metabolic substrate(s). To this end, organ perfusion studies under a variety of conditions will be undertaken to gain insight into the symbiotic relationship in which the individual body organs singularly and/or collectively contribute to the energy metabolism of red blood cells.